A prominent comedian convicted of performing a sex act on his four-year-old daughter has finally been ordered to start serving his sentence 22 months after admitting the offence.

The man, who has permanent name suppression, pleaded guilty in March 2011 to performing an indecent act on his daughter and was initially discharged without conviction.

Auckland District Court Judge Philippa Cunningham, who discharged him, said he was a talented New Zealander and the consequences of a conviction outweighed his offending.

The Crown took the rare step of going to the High Court for a judicial review, arguing that discharging the man was not appropriate. The High Court ordered the District Court to resentence him.

In July this year Judge Mark Perkins sentenced the man to eight months home detention, telling him "it is clear this was grave offending".

The Auckland comedian then appealed that sentence.

He argued he should have again been discharged without conviction because of the impact on his career - or at least been given a less restrictive community-based sentence.

Today a full bench of the Court of Appeal rejected his argument and told him to report to Auckland Central Police Station in January "to make arrangements to begin serving his sentence".

The justices told the comedian his "offending was serious and requires both denunciation and accountability".

Referring to the comedian by the letter Z, they said: "We do not see how it can sensibly be said that this offending is not of a high level of gravity. It is apparent from the material before us that the offending initially had a significant impact on the victim and her mother, although it was clear by the time of Judge Perkins' re-sentencing that Z had managed to re-establish a successful relationship with his daughter and had a working relationship with her mother.

"After he [the comedian] was discharged without conviction, he was able to begin to rebuild his career, not as a presenter but as a writer and producer. His employer's legal counsel noted in a letter to the court that the media and those associated with its funding are extremely sensitive to public opinion and expressed the fear that if Z did not receive a discharge, this rebuilding process would be set back.

"This was because, without a discharge, it was unlikely that Z could ever act as a presenter again and it would be difficult to give him public credit for his writing and production work. As it was put, Z's career would 'plateau'.

"There is no doubt that Judge Perkins was well aware of the consequences of a conviction on Z's career and acknowledged that they were serious. He also noted that the offending had had a serious impact upon Z's family, but concluded that, with the passage of time, some of that impact had been ameliorated, particularly as Z was able to have proper contact with his children.

"However, the judge considered that, to a significant extent, the adverse consequences had already been suffered and would not be significantly exacerbated by the refusal of a discharge. We see no error in that assessment and agree with it."

The Court of Appeal also recognised the comedian is a talented performer, but told him if he had not received home detention, he would have faced jail because of the seriousness of the offending.

"Z has addressed his alcohol abuse problem and has faced up to the enormity of his actions. He is a talented person who committed what was undoubtedly a one-off, out-of-character offence. On the other hand, intoxication is not an available explanation for this offending and, on any view, the offending was serious and requires both denunciation and accountability," the justices said.

"Looking at the matter overall, we consider that, if Z had not been sentenced to home detention, he must have been sentenced to a short term of imprisonment given the nature and circumstances of the offending. Accordingly, home detention in this case can properly be seen as commuting what would otherwise have been a short sentence of imprisonment.

"We do not see any of the community-based options as being sufficient to reflect the need for denunciation and accountability."

In handing down the home detention sentence originally, Judge Perkins told the court the offending occurred on December 9, 2009, after the man returned from a Christmas party in an intoxicated state.

He tried to have sex with his then-wife but she rejected him and they went to sleep. Later in the evening the child came into the bed and slept between the couple.

The man woke up and proceeded to sexually assault the child.

He claimed to have no memory of the event but Judge Perkins said this was inconsistent with a later statement that he thought the person was his wife.

Judge Perkins said it was a serious sexual assault.

The mother woke up during the act and called police.

The offender had dealt with his alcohol issues and both the Family Court and Child Youth and Family "harbour no continuing concerns".

The man had shared custody of their child and had made a clear expression of remorse, the judge said.

"You are horrified at your own offending."

There was no sign of trauma in the child and there had been significant reconciliation between the mother, child and father.